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| United States Patent |
6,188,368
|
|
Koriyama
, et al.
|
February 13, 2001
|
Slot antenna
Abstract
A slot antenna comprising a dielectric substrate, a high-frequency signal
transmission line formed on one surface of said dielectric substrate and
having an open end, and a ground layer formed on the other surface of said
dielectric substrate, said ground layer having a slot at a position
opposed to the open end of said transmission line, wherein a dielectric
plate for impedance matching is laminated on the surface of said ground
layer on the side where said slot is formed so as to cover said slot. The
slot antenna not only features a high antenna efficiency but also can be
easily and cheaply produced by a layer-laminating method which is a
generally employed technology for producing multi-layer wiring substrates.
Besides, the slot antenna has a very simple structure which is small in
size and is light in weight, and can be very well adapted to the systems
that require these characteristics.
| Inventors:
|
Koriyama; Shinichi (c/o Kyocera Corporation, 1-4, Yamashita-cho, Kokubu, Kagoshima-ken, JP);
Kitazawa; Kenji (c/o Kyocera Corporation, 1-4, Yamashita-cho, Kokubu, Kagoshima-ken, JP);
Minamiue; Hidehiro (c/o Kyocera Corporation, 1-4, Yamashita-cho, Kokubu, Kagoshima-ken, JP)
|
| Appl. No.:
|
258830 |
| Filed:
|
February 26, 1999 |
| Current U.S. Class: |
343/767; 343/770; 343/872 |
| Intern'l Class: |
H01Q 013/00 |
| Field of Search: |
343/767,770,769,700 MS,872
333/24 C
|
References Cited
U.S. Patent Documents
| 4130822 | Dec., 1978 | Conroy | 343/767.
|
| 4197545 | Apr., 1980 | Favaloro et al. | 343/700.
|
| 4431996 | Feb., 1984 | Milligan | 343/708.
|
| 5392152 | Feb., 1995 | Higgins et al. | 359/333.
|
| 5489913 | Feb., 1996 | Raguenet et al. | 343/767.
|
| 5631659 | May., 1997 | Evans et al. | 343/700.
|
Primary Examiner: Ho; Tan
Claims
What is claimed is:
1. A slot antenna comprising a dielectric substrate, a high-frequency
signal transmission line formed on one surface of said dielectric
substrate and having an open end, and a ground layer formed on the other
surface of said dielectric substrate, said ground layer having a slot at a
position opposed to the open end of said transmission line, wherein
a dielectric plate for impedance matching is laminated on the surface of
said ground layer on the side where said slot is formed so as to cover
said slot.
2. The slot antenna according to claim 1, wherein a conductor electrically
connected to said ground layer is arranged around or inside said
dielectric plate for impedance matching so as to surround said slot.
3. A wiring board equipped with the slot antenna of claim 1.
4. The wiring board according to claim 3, wherein a semiconductor element
is mounted on the dielectric substrate.
5. A slot antenna comprising a dielectric substrate, a high-frequency
signal transmission line formed on one surface of said dielectric
substrate and having an open end, and a ground layer formed on the other
surface of said dielectric substrate, said ground layer having a slot at a
position opposed to the open end of said transmission line,
wherein a dielectric plate for impedance matching is laminated on the
surface of said ground layer on the side where said slot is formed so as
to cover said slot, the plate having a thickness h (mm) that satisfies the
condition represented by the following formula (1):
53.7/(f.multidot..di-elect
cons..sub.1.sup.1/2).ltoreq.h.ltoreq.89.4/(f.multidot..di-elect
cons..sub.1.sup.1/2) (1)
where .di-elect cons..sub.1 is a dielectric constant of the dielectric
plate for impedance matching, and f is a frequency (GHz) of the
transmitted signals.
6. A slot antenna comprising a dielectric substrate, a high-frequency
signal transmission line formed on one surface of said dielectric
substrate and having an open end, and a ground layer formed on the other
surface of said dielectric substrate, said ground layer having a slot at a
position opposed to the open end of said transmission line, wherein
a dielectric plate for impedance matching is laminated on the surface of
said ground layer on the side where said slot is formed so as to cover
said slot, and
wherein the length ML (mm) from the open end of said transmission line to a
portion corresponding to the center of said slot, and the length SL (mm)
of said slot in a direction at right angles with the direction in which
said transmission line extends, satisfy the conditions represented by the
following formulas (2) and (3):
62.7/(f.multidot..di-elect
cons..sub.2.sup.1/2).ltoreq.ML.ltoreq.125/(f.multidot..di-elect
cons..sub.2.sup.1/2) (2)
171/[(f.multidot.[(.di-elect cons..sub.1 +.di-elect cons..sub.2)/2].sup.1/2
].ltoreq.SL.ltoreq.250/(f.multidot.[(.di-elect cons..sub.1 +.di-elect
cons..sub.2)/2].sup.1/2 ] (3)
where .di-elect cons..sub.1 is a dielectric constant of the dielectric
plate for impedance matching, and .di-elect cons..sub.2 is a dielectric
constant of the dielectric substrate, and f is a frequency (GHz) of the
transmitted signals.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a slot antenna adapted to transmitting or
receiving high-frequency signals of chiefly microwaves or millimeter
waves.
2. Description of the Prior Art
In recent years, data have been transmitted in a wireless manner and on a
personal basis as represented by portable telephones. Under such
circumstances, it has been desired to transmit large amounts of data at
higher speeds. For this purpose, semiconductor elements (high-frequency
semiconductor elements) have been developed that operate in high-frequency
regions such as of millimeter waves (30 to 300 GHz).
There have further been proposed various applied systems using
high-frequency semiconductor elements that work on millimeter
electromagnetic waves, as represented by a between-the-car radar and a
wireless LAN. For example, in the Electronics Society, Japanese Academy of
Electronic Data Communication, 1995, a between-the-car radar (see SC-7-6),
a cordless camera system (see C-137), a high-speed wireless LAN (see
C-139) and the like systems have been proposed.
These systems all utilize radio waves, and signals are exchanged through
antennas between the system and space in which radio waves propagate. A
variety kinds antennas have heretofore been studied for dealing with
high-frequency signals as can be represented by a microstrip antenna, a
horn antenna, a slot antenna and the like antennas.
The slot antenna has a structure in which a high-frequency signal
transmission line such as a microstrip line is formed on one surface of a
dielectric substrate, a ground layer is formed on the other surface
thereof, a slot is formed in the ground layer at a position opposed to an
open end of the transmission line, and the transmission line and the slot
are electromagnetically coupled together. The slot antenna having such a
structure is advantageous in that it can be easily produced by utilizing a
general layer-laminating technology, it is particularly cheaply produced
among the above-mentioned various kinds of antennas, and it is very suited
for the systems that must be constructed in small sizes and in light
weights.
However, the existing slot antennas have a defect of low efficiency (signal
transmission characteristics) and, hence, it has been demanded to improve
the efficiency.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a slot
antenna capable of transmitting high-frequency signals maintaining a high
efficiency.
According to the present invention, there is provided a slot antenna
comprising a dielectric substrate, a high-frequency signal transmission
line formed on one surface of said dielectric substrate and having an open
end, and a ground layer formed on the other surface of said dielectric
substrate, said ground layer having a slot at a position opposed to the
open end of said transmission line, wherein
a dielectric plate for impedance matching is laminated on the surface of
said ground layer on the side where said slot is formed so as to cover
said slot.
In the conventional slot antenna, it is considered that there exists a
mismatching between the impedance of the slot portion and the impedance of
external space in which the electromagnetic waves propagate,
high-frequency signals are reflected by the slot portion due to the
mismatching and, as a result, the efficiency of the antenna remains low.
According to the present invention, on the other hand, the dielectric
plate for impedance matching is provided so as to cover the slot, whereby
mismatching of the impedance is suppressed, high-frequency signals are not
reflected by the slot portion, and a high antenna efficiency is
accomplished.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view illustrating a slot antenna according to the present
invention;
FIG. 2 is a side sectional view (X--X sectional view) of the slot antenna
of FIG. 1;
FIG. 3 is a side sectional view illustrating a slot antenna according to
the most preferred embodiment of the present invention; and
FIG. 4 is a side sectional view illustrating a wiring board equipped with
the slot antenna of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1 and 2, the slot antenna of the present invention is
provided with a dielectric substrate 1 which has, on one surface thereof,
a high-frequency signal transmission line 2 with an open end 2a, and has,
on the other surface thereof, a ground layer 3. The ground layer 3 has a
slot 4 formed at a position opposed to the open end 2a.
A dielectric plate 5 for impedance matching is stuck with an adhesive or
the like to the ground layer 3 so as to completely cover the slot 4.
In the thus constituted slot antenna, the high-frequency signals
transmitted through the transmission line 2 are fed to the slot 4 owing to
the electromagnetic coupling formed by a combination of the open end 2a
and the slot 4. Here, the slot 4 has an impedance different from the
impedance of external space. Due to mismatching of impedance, therefore,
the high-frequency signals are reflected by the slot 4 despite it is
attempted to directly radiate the electromagnetic waves from the slot 4
into the external space. According to the present invention, however,
mismatching of impedance is relaxed since the slot is covered with the
dielectric plate 5 for impedance matching. Therefore, the electromagnetic
waves are highly efficiently radiated into the external space and the
antenna efficiency is enhanced.
According to the present invention, it is desired that the dielectric plate
5 for impedance matching has a thickness h (mm) that satisfies the
condition represented by the following formula (1):
53.7/(f.multidot..di-elect
cons..sub.1.sup.1/2).ltoreq.h.ltoreq.89.4/(f.multidot..di-elect
cons..sub.1.sup.1/2) (1)
where .di-elect cons..sub.1 is a dielectric constant of the dielectric
plate for impedance matching, and f is a frequency (GHz) of the
transmitted signals.
When the dielectric plate 5 has a thickness h that lies outside the
above-mentioned range, the action for relaxing the mismatching between the
impedance of the slot 4 and the impedance of the external space decreases,
and the signals tend to be reflected by the slot 4.
In order to enhance the electromagnetic coupling between the high-frequency
signal transmission line 2 and the slot 4, furthermore, it is desired that
the slot 4 has a size that satisfies the following conditions. That is, it
is desired that the length ML (mm) from the open end 2a of the
transmission line 2 to a portion corresponding to the center of the slot
4, and the length SL (mm) of the slot 4 in a direction at right angles
with the direction in which the transmission line 2 extends, satisfy the
conditions represented by the following formulas (2) and (3):
62.7/(f.multidot..di-elect
cons..sub.2.sup.1/2).ltoreq.ML.ltoreq.125/(f.multidot..di-elect
cons..sub.2.sup.1/2) (2)
171/[f.multidot.[(.di-elect cons..sub.1 +.di-elect cons..sub.2)/2].sup.1/2
].ltoreq.SL.ltoreq.250/[f.multidot.[(.di-elect cons..sub.1 +.di-elect
cons..sub.2)/2].sup.1/2] (3)
where .di-elect cons..sub.1 is a dielectric constant of the dielectric
plate for impedance matching, .di-elect cons..sub.2 is a dielectric
constant of the dielectric substrate, and f is a frequency (GHz) of the
transmitted signals.
When the lengths ML and SL satisfy the above-mentioned formulas (2) and
(3), the electromagnetic coupling between the transmission line 2 and the
slot 4 becomes the greatest, and the signals are reflected least by the
slot 4.
Though FIG. 1 shows the slot 4 of a rectangular shape, there is no
particular limitation on the shape of the slot which, therefore, may be of
an elliptical shape. It is desired that the conditions of the
above-mentioned formulas (2) and (3) are satisfied even when the slot 4 is
of an elliptical shape, as a matter of course.
In the present invention, there is no particular limitation on the size
(width) of the dielectric plate 5 for impedance matching so far as the
slot 4 is completely covered by the dielectric plate 5. For example, the
dielectric plate 5 may have a size just for covering only the periphery of
the slot 4 as shown in FIG. 2 or may have a size large enough for covering
nearly the whole surface of the ground layer 3.
It is further desired that the dielectric plate 5 is provided with a
conductor electrically connected to the ground layer 3 so as to surround
the slot 4 that is covered by the dielectric plate 5. FIG. 3 illustrates a
major portion of the slot antenna provided with such a conductor.
In FIG. 3, the ground layer 3 is covered by the dielectric plate 5 which
includes therein a plurality of via conductors 8 which are electrically
connected to the ground layer 3 so as to surround the slot 4. That is, in
a state shown in FIG. 3, a portion of the dielectric plate 5 surrounded by
the via conductors 8 produces a function for matching the impedance. The
electromagnetic waves radiated from the slot 4 are radiated into the
external space through the dielectric plate 5. Without such via conductors
8, the reflection of signals by the slot 4 can be suppressed to be not
larger than, for example, -10 dB. However, the electromagnetic waves from
the slot 4 are partly diffused in the dielectric plate 5 and propagate in
the circumferential directions. By providing the via conductors 8 as shown
in FIG. 3, the electromagnetic waves diffused in the dielectric plate 5
are shut off by the via conductors. Therefore, the electromagnetic waves
from the slot 4 are all radiated into the external space to further
enhance the antenna characteristics.
It is desired that the gap among the plurality of via conductors 8 is not
larger than one-fourth the wavelength of the high-frequency signals that
are transmitted from the standpoint of producing a sufficient degree of
effect for shielding the electromagnetic waves. It is further possible to
provide a plate-like continuous conductor instead of the plurality of via
conductors 8. It is desired that the plurality of via conductors 8 are
provided along the slot 4 so as to surround it. When the dielectric plate
5 has a small size as shown in FIG. 2, the via conductors 8 or the
conductor plate may be provided to surround the dielectric plate 5.
In the slot antenna of the present invention shown in FIGS. 1 to 3, the
dielectric substrate 1 and the dielectric plate 5 for impedance matching
can be formed of a widely known substrate material such as an inorganic
material, e.g., Al.sub.2 O.sub.3, Si.sub.3 N.sub.4, AlN or glass ceramics,
an organic resin, e.g., bismaleimide resin or polyphenylene oxide, or an
organic resin/inorganic filler composite material. These members may be
made of the same dielectric material. When the dielectric substrate 1 and
the dielectric plate 5 for impedance matching are formed of inorganic
materials, the inorganic materials may be so selected as can be
simultaneously fired, offering such an advantage that the slot antenna is
produced at one time by the simultaneous firing.
The ground layer 3 and the via conductors 8 can be formed of a known
conducting material such as W, Mo, Mo--Mn, Cu, Au or Ag. In order to
decrease the transmission loss of high-frequency signals, it is desired to
use a low-resistance conductor such as Cu, Au or Ag.
The above-mentioned slot antenna of the present invention not only features
a high antenna efficiency but also can be easily and cheaply produced by a
layer-laminating method which is a generally employed technology for
producing multi-layer wiring substrates. Besides, the slot antenna has a
very simple structure which is small in size and is light in weight, and
can be very well adapted to the systems that require the above-mentioned
characteristics. In particular, the dielectric substrate 1 permits a
semiconductor element to be directly mounted thereon and can, hence, be
easily fabricated together with a wiring board on which semiconductor
elements are mounted.
FIG. 4 illustrates the structure of a wiring board in which the slot
antenna of the present invention is formed integrally together therewith.
In this wiring board, the high-frequency signal transmission line 2 is
formed in the shape of a circuit pattern on one surface of the dielectric
substrate 1, and the ground layer 3 having slot 4 is formed on the the
surface of the dielectric substrate 1. That is, as described earlier, the
slot 4 is formed at a position opposed to the open end 2a of the
transmission line 2, and the transmission line 2 and the slot 4 are
electromagnetically coupled together thereby to constitute a fundamental
structure of the slot antenna.
Furthermore, a dielectric layer 7 is laminated on the ground layer 3, and a
plurality of via conductors 8 electrically connected to the ground layer 3
are formed in the dielectric layer 7 so as to surround the slot 4. The
dielectric layer 7 corresponds to the above-mentioned dielectric plate 5
for impedance matching. Here, however, what possesses the function for
matching the impedance is only a portion surrounded by the via conductors
8. In FIG. 4, therefore, this portion is designated at 5.
A semiconductor element 9 such as silicon chip or the like is mounted on
the surface of the dielectric substrate 1 on the side of the transmission
line 2, and is connected to the high-frequency signal transmission line 2
by bonding wires. Furthermore, a cap 10 made of a conductor such as metal
is adhered to the dielectric substrate 1. Owing to the cap 10, the
semiconductor element 9 is air-tightly maintained.
In the wiring board having the above-mentioned structure, the slot antenna
of the present invention is easily formed therein integrally together
therewith relying upon the known multi-layer forming technology. It can
therefore be understood that the wiring board is small in size, light in
weight, and is cheaply produced. In the wiring board, it is allowable to
form the dielectric substrate 1 in a multi-layer structure as a matter of
course. For instance, the transmission line 2 that electromagnetically
couples to the slot 4 may be formed on the inside, and the semiconductor
element 9 may be mounted on the uppermost layer.
The invention will now be described by way of examples.
EXAMPLE 1
A linear conductor passage of a predetermined pattern was formed on one
surface of a green sheet of alumina having a dielectric constant of 8.9 by
metalizing tungsten, and a conductor layer having a slot was formed on the
other surface of the green sheet by metalizing tungsten, followed by
firing simultaneously in order to form a dielectric substrate 1, a
high-frequency signal transmission line (microstrip line) 2 and a ground
layer 3 having a slot 4 integrally together. Thereafter, gold was plated
on the surfaces of the transmission line 2 and the ground layer 3 to
prepare a slot antenna for comparison (sample No. 0).
In the slot antenna for comparison, the thickness of the dielectric
substrate 1, the length ML from the open end 2a of the transmission line 2
to a portion corresponding to the center of the slot 4, and the length SL
of the slot 4 in a direction at right angles with the direction in which
the transmission line 2 extends, were as follows:
Thickness of the dielectric substrate: 0.2 mm
ML: 3.0 mm
SL: 6.6 mm
Next, a dielectric plate 5 for impedance matching (20 mm high, 10 mm wide
and 2.4 mm thick) made of the same material as the dielectric substrate 1
was adhered on the surface of the slot 4 with an epoxy adhesive agent in
order to prepare a slot antenna of the present invention (sample No. 1).
Furthermore, various slot antennas (samples Nos. 2 to 66) were prepared in
the same manner as described above by changing the lengths ML, SL and
thickness (h) of the dielectric plate 5.
In order to evaluate the transmission characteristics, a conversion line
from the microstrip line into a grounded coplanar waveguide was provided
at an end on the side opposite to the open end 2a of the transmission line
2 of each of the slot antennas produced as described above. A
coplanar-type probe of a network analyzer was connected to the
conductor-backed coplanar waveguide in order to measure the reflection
characteristics of high-frequency signals of 10 GHz or 60 GHz. The results
were as shown in Tables 1 and 2.
For some slot antennas, a conductor layer of Ag was adhered around the
dielectric plate 5 to evaluate the transmission characteristics in the
same manner as described above. The results were as shown in Tables 1 and
2.
Tables 1 and 2 show the ranges of h, ML and SL defined by the
above-mentioned formulas (1) to (3) as F(h), F(ML) and F(SL).
It will be understood from the results of Tables 1 and 2 that when h, ML
and SL satisfy the conditions of the formulas (1) to (3), the reflection
becomes not larger than -10 dB, and highly efficient antennas are
obtained. It will be further understood that the antenna efficiency is
further improved by forming a conductor layer around the dielectric plate
5 for impedance matching.
TABLE 1
Frequency: 10 GHz
S11 (dB)
without with
Sample ML SL h conductor conductor
No. (mm) (mm) (mm) layer layer
0 3.0 6.6 not formed -2 --
*1 3.0 6.6 1.2 -3 -4
2 3.0 6.6 1.8 -18 -23
3 3.0 6.6 2.4 -36 -37
4 3.0 6.6 3.0 -22 -22
*5 3.0 6.6 3.6 -7 -8
*6 1.8 6.6 2.4 -8 --
7 2.1 6.6 2.4 -24 --
8 2.4 6.6 2.4 -30 --
9 3.6 6.6 2.4 -31 --
10 4.2 6.6 2.4 -27 --
*11 4.5 6.6 2.4 -9 --
*12 3.0 5.4 2.4 -6 --
13 3.0 5.7 2.4 -20 --
14 3.0 6.0 2.4 -27 --
15 3.0 7.2 2.4 -30 --
16 3.0 8.4 2.4 -26 --
*17 3.0 9.0 2.4 -8 --
*18 1.8 5.7 1.8 -3 --
19 2.1 5.7 1.8 -10 --
20 4.2 5.7 1.8 -14 --
*21 4.5 5.7 1.8 -5 --
*22 1.8 5.7 3.0 -4 --
23 2.1 5.7 3.0 -16 --
24 4.2 5.7 3.0 -13 --
*25 4.5 5.7 3.0 -5 --
*26 1.8 8.4 1.8 -3 --
27 2.1 8.4 1.8 -10 --
28 4.2 8.4 1.8 -11 --
*29 4.5 8.4 1.8 -4 --
*30 1.8 8.4 3.0 -3 --
31 2.1 8.4 3.0 -12 --
32 4.2 8.4 3.0 -10 --
*33 4.5 8.4 3.0 -3 --
F(h) = 1.80-3.0 (mm)
F(ML) = 2.10-4.20 (mm)
F(SL) = 5.74-8.39 (mm)
Samples marked with * are those that do not satisfy the conditions of the
formulas (1), (2) and (3) (the same holds in Tables 2 and 3, too).
TABLE 2
Frequency: 60 GHz
S11 (dB)
without with
Sample ML SL h conductor conductor
No. (mm) (mm) (mm) layer layer
*34 0.5 1.1 0.2 -6 -7
35 0.5 1.1 0.3 -20 -30
36 0.5 1.1 0.4 -35 -39
37 0.5 1.1 0.5 -17 -22
*38 0.5 1.1 0.6 -8 -9
*39 0.3 1.1 0.4 -5 --
40 0.35 1.1 0.4 -12 --
41 0.4 1.1 0.4 -19 --
42 0.6 1.1 0.4 -23 --
43 0.7 1.1 0.4 -20 --
*44 0.75 1.1 0.4 -7 --
*45 0.5 0.9 0.4 -4 --
46 0.5 0.95 0.4 -11 --
47 0.5 1.0 0.4 -30 --
48 0.5 1.2 0.4 -25 --
49 0.5 1.4 0.4 -16 --
*50 0.5 1.5 0.4 -8 --
*51 0.3 0.95 0.3 -3 --
52 0.35 0.95 0.3 -12 --
53 0.7 0.95 0.3 -14 --
*54 0.75 0.95 0.3 -3 --
*55 0.3 0.95 0.5 -4 --
56 0.35 0.95 0.5 -15 --
57 0.7 0.95 0.5 -10 --
*58 0.75 0.95 0.5 -3 --
*59 0.3 1.4 0.3 -3 --
60 0.35 1.4 0.3 -13 --
61 0.7 1.4 0.3 -10 --
*62 0.75 1.4 0.3 -3 --
*63 0.3 1.4 0.5 -3 --
64 0.35 1.4 0.5 -15 --
65 0.7 1.4 0.5 -14 --
*66 0.75 1.4 0.5 -3 --
F(h) = 0.30-0.50 (mm)
F(ML) = 0.35-0.70 (mm)
F(SL) = 0.96-1.40 (mm)
EXAMPLE 2
A variety of slot antennas (samples Nos. 67 to 83) were prepared in the
same manner as in Example 1 but using a glass ceramics having a dielectric
constant of 5.6 as a dielectric material for constituting the dielectric
plate 5 for impedance matching, and the reflection of high-frequency
signals was measured at 60 GHz. For some slot antennas, a conductor layer
of Ag was adhered around the dielectric plate 5 to evaluate the
transmission characteristics in the same manner as described above. The
results were as shown in Table 3.
It will be understood from the results of Table 3 that when h, ML and SL
satisfy the conditions of the formulas (1) to (3), the reflection becomes
not larger than -10 dB, and highly efficient antennas are obtained. It
will be further understood that the antenna efficiency is further improved
by forming a conductor layer around the dielectric plate 5 for impedance
matching.
TABLE 3
Frequency: 60 GHz
S11 (dB)
without with
Sample ML SL h conductor conductor
No. (mm) (mm) (mm) layer layer
*67 0.5 1.3 0.3 -7 -8
68 0.5 1.3 0.4 -14 -20
69 0.5 1.3 0.5 -32 -34
70 0.5 1.3 0.6 -23 -24
*71 0.5 1.3 0.7 -8 -9
*72 0.3 1.3 0.5 -6 -8
73 0.35 1.3 0.5 -16 -20
74 0.4 1.3 0.5 -28 -31
75 0.6 1.3 0.5 -30 -35
76 0.7 1.3 0.5 -18 -19
*77 0.75 1.3 0.5 -9 -9
*78 0.5 1.0 0.5 -3 -4
79 0.5 1.1 0.5 -10 -12
80 0.5 1.2 0.5 -19 -25
81 0.5 1.4 0.5 -22 -31
82 0.5 1.5 0.5 -17 -20
*83 0.5 1.6 0.5 -6 -8
F(h) = 0.38-0.63 (mm)
F(ML) = 0.35-0.70 (mm)
F(SL) = 1.06-1.55 (mm)
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